The goal of this research is to provide further information concerning the basic processes regulating the production of functionally important proteins by the neuron. The specific aim is to determine if the metabolism of neurosecretory protein is linked to the functional activity of the neurosecretory cell. Three projects are proposed to approach different aspects of this question, and each will be carried out in a particularly advantageous subsystem of the simple nervous system of the mollusk, Aplysia: 1) Using the bag cells of the abdominal ganglion, which produce and secrete a peptide egg-laying hormone, we will ask if massive experimentally-induced secretion is followed by enhanced synthesis of the secretory protein. Preliminary experiments indicate that this is the case, and if these are confirmed, we will then determine whether the "trigger" involves presynaptic input, action potential generation, or secretion. We will then attempt a biochemical characterization of the regulatory mechanism. 2) Using a long interganglionic neurosecretooy tract in this nervous system, we will ask if experimentally-induced secretion induces a change in either the rate of axonal transport of neurosecretory material or the quantity that is transported. If a change is observed, we will then search for the "trigger". 3) Finally, we will attempt to determine whether synaptic inhibition and the application of putative inhibitory transmitters can reduce the rate of synthesis of presumptive neurosecretory proteins by individual identified neurons of the abdominal ganglion.